Wave asymmetry and particle orbits in irregular wave models

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Abstract

Water particle orbits are key elements in the Lagrange wave formulation. The stochastic
Miche implementation of the Lagrange model is a linear Gaussian 2D or 3D space-time
model which exhibit typical non-linear wave characteristics when transformed to Eulerian
coordinates. This paper investigates the statistical relation between the degree of front-back
asymmetry of individual waves and the orbit orientation for the particle
located at the wave maximum at the point of observation.
It is shown that in the Lagrangian model with statistical front-back symmetry, for individual waves
there is a clear connexion between the degree of individual wave asymmetry and the orientation of the randomly deformed elliptic orbit: a steep front correlates with upward tilt,
a steep back is correlated with a downward tilt. This holds both for waves observed in
time and in space, and the dependence is stronger for large
amplitude waves than for smaller ones.
The dependence is strongly dependent on the depth and on the significant steepness
and spectral width. Inclusion of the average Stokes drift
has a moderate effect on the dependence. For models with forced front-back asymmetry
there is both a systematic dependence and a statistical correlation between asymmetry
and tilt; for large amplitude waves the systematic relation dominates. The conclusions
are based on Fourier simulations of Gauss-Lagrange waves of 1st and 2nd order
with wind-sea Pierson-Moskowitz spectrum and a narrow swell JONSWAP spectrum.

Detaljer

Författare
Enheter & grupper
Externa organisationer
  • IFREMER Centre de Brest
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Sannolikhetsteori och statistik
  • Strömningsmekanik och akustik
Originalspråkengelska
ArtikelnummerA27
Antal sidor19
TidskriftJournal of Fluid Mechanics
Volym905
StatusPublished - 2020 dec 25
PublikationskategoriForskning
Peer review utfördJa